Performance analysis of compliant cylindrical intershaft seal

Area of Science:

• Aerospace Engineering
• Mechanical Engineering
• Fluid Dynamics

Background:

• Intershaft seals in dual-rotor turbofan engines are critical for performance and longevity.
• Traditional labyrinth seals suffer from increased leakage after tooth wear.
• A novel compliant cylindrical aerodynamic seal is proposed to address these limitations.

Purpose of the Study:

• To introduce a compliant cylindrical aerodynamic intershaft seal structure.
• To analyze the force conditions and aeroelastic coupling of the floating seal ring.
• To evaluate leakage characteristics under various operating conditions and rotor rotational directions.

Main Methods:

• Analysis of the force condition on the floating seal ring.
• Development of an aeroelastic coupling method for seal ring eccentricity.
• Computational fluid dynamics (CFD) analysis of leakage characteristics for different seal structures and operating conditions (homodromic/counter-rotating).

Main Results:

• The hydrodynamic effect is significantly enhanced under homodromic rotation and weakened under counter-rotating conditions.
• Seal performance is influenced by rotor rotational direction, seal width, rotor precession eccentricity, rotational speed, and rotor radius.
• The compliant cylindrical hydrodynamic gas film seal demonstrates superior performance in homodromic rotation.

Conclusions:

• The proposed compliant cylindrical aerodynamic intershaft seal effectively mitigates leakage issues associated with tooth wear.
• Rotor rotational direction is a key factor affecting the hydrodynamic seal performance.
• The hydrodynamic seal is more effective in homodromic rotation for dual-rotor turbofan engines.